The present invention relates to an apparatus for treating fuel prior to entry into the intake manifold of an internal combustion engine, and more particularly to an apparatus for gasifying that portion of the fuel which will not vaporize under normal conditions, or which most readily condenses once vaporized.
Unvaporized or ungasified portions of fuel normally do not burn within the cylinder and are lost to the combustion process and so wasted. The greatest portion of this unburned (wasted) fuel is not sufficiently volatile to gasify in the time spent within the cylinders. As the wasted fuel passes through the engine to the exhaust, some marginal parts appear in an exhaust gas analysis as partially burned carbon monoxide (CO). Other marginal parts appear as unburned hydrocarbons (HC). While detecting some of the unburned products ordinary exhaust gas analysis procedures do not detect a great portion of these unburned fuel constituents. The residual heavy varnishes and tars associated with the unburned portions of fuel recondense and drop out of the exhaust gas samples and thus fail to register as pollutants which are normally discharged by the exhaust pipe to the atmosphere.
Mechanical designers have long been concerned with developing an efficiently operating internal combustion engine. In the United States, the automobile is responsible for a significant percentage of pollutants found in the atmosphere, and the consumption of vast amounts of the petroleum available in this country. Accordingly, automobile engine designers have expended considerable efforts to reduce the fuel consumption and pollution-developing characteristic of internal combustion engines. This interest has led to various engine designs, many of which have achieved some success. However, there remains the need for more efficient engines.
In addition to the engine designs themselves, automotive engineers have proposed various devices for use with internal combustion engines to increase engine efficiency. This equipment is frequently directed to improving the efficiency of the engine combustion phase, such as ignition systems, pre-heaters, and the like, Again, some of this apparatus has experienced success, but none has made a significant advance in the field.
Other proposals for increasing combustion efficiency have included the redesign of the combustion and/or the engine carburetor. Redesign of the carburetor improves engine combustion and mechanical efficiency by improving the uniformity and quality of the fuel-air mixture entering the several engine combustion chambers. For example, combustion efficiency has to some extent been improved by increasing fuel vaporization by means of devices such as centrifugal separators, charge stratifiers, screens placed in the flow lines, etc. While there may be some improvement in engine efficiency by using these devices, other problems may arise such as unreliability and non-uniformity of operation, especially during cold-engine operation or during periods of high acceleration. Furthermore, such devices are often difficult to control, making these devices of marginal value at best.
A serious drawback to the above-discussed known fuel vaporization device is the inability to adequately operate on the heavy ends of modern fuels, that is, those fuel components having the high molecular weight. Heavy ends atomize sufficiently to pass through an engine but do not readily vaporize. Therefore, unless specially handled, the heavy ends will be entrained in the fuel-air mixture entering the engine combustion chamber with resulting combustion inefficiencies. The devices discussed above, often provide a mechanism for removing some of the heavy ends from the fuel-air mixture, but do not utilize these heavy ends when removed. Such known devices are therefore wasteful and inefficient.
One known method for vaporizing heavy ends has been to heat the fuel or the fuel-air mixture. While this method is potentially effective, it has not been entirely successful because the complex composition of modern fuels makes it difficult to provide a simple device which vaporizes all of the heavy ends present in a given fuel without overheating the air in which the fuel is entrained. Furthermore, an engine may at different times be used with a variety of fuels, thus making a fixed temperature heating system inefficient. One known device operates at temperatures high enough to vaporize all heavy ends in the fuel. This device is at best wasteful of energy, and may even be dangerous from a standpoint of risking a high temperature explosion. As a compromise, devices have been developed which generate a type of "average temperature", with a resultant efficient vaporization of only some, but not all of the heavy ends.
Other presently known vaporizing devices operate at less than maximum performance as a result of heat loss in the vaporized fuel flowing back into the mainstream of the engine fuel-air mixture. Reliquification of the heavy ends due to such heat loss would tend to negate the effect of the vaporizing device. There could also result a fuel-air mixture which varies in quality among the engine cylinders, with only those cylinders located near the device receiving fully vaporized fuel and uniform mixtures. Such non-uniformity in mixture would cause engine control problems as well as engine efficiency losses.
Therefore, to assure efficient, safe engine operating, the heat output of a fuel vaporizer must be carefully controlled so as to heat the heavy ends in an atmosphere too rich to burn while heating. It is this lack of control which is most likely responsible for the inefficient, ineffective and potentially dangerous operation of known devices. Such inefficiency and/or ineffectiveness presents serious doubts to the future use of these known fuel vaporizing devices as the solution to the problem of improving the performance of internal combustion engines.
Recently, strict exhaust pollution level constraints have been placed on modern internal combustion engines in general, and on automobile engines in particular. Most modern pollution control devices treat engine exhaust and therefore are directed at curing the symptoms of inefficient combustion rather than the causes. Thus, while pollution levels are decreased, automobile costs and fuel consumption are increased.
The exhaust from automobile engines generally contains hydrocarbon, carbon monoxide and oxides of nitrogen such as nitric oxide and nitrous oxide. Modern pollution control devices such as the catalytic converter help to control the hydrocarbon and carbon monoxide levels, but do not effectively control the nitrogen oxide levels in engine exhausts. Therefore, pollution from engine exhausts remains a serious problem.
The drawbacks of the piston-type internal combustion engine which are discussed above have to some extent recently resulted in the commercialization of the long-known rotary engine. Some of the problems characteristic of the piston engine have been overcome, yet the rotary engine suffers from its own drawbacks. As an example, the piston engine runs relatively hot, and hence nitrous oxide is formed. Yet the piston engine is low in its carbon monoxide and hydrocarbon levels. The rotary engine, on the other hand, runs cooler and hence the level of nitrous oxide is low. However, the levels of carbon monoxide and hydrocarbon are high. Fuel consumption is also high due to low expansion ratios. It should be apparent from the above, that the problem of exhaust pollution has by no means been overcome.
While some presently known devices are directed to the problem of providing efficient combustion, and other devices purportedly provide exhaust pollution control, there are no known engines and no known devices which provide efficient engine operation under normal engine conditions. Therefore, a great need exists for a device which effectively enhances both the operating efficiency and the freedom from exhaust pollution in an internal combustion engine.
The present invention relates to an internal combustion engine provided with a recirculating fuel-feed mechanism for increasing the efficiency of the combustion phases of the internal combustion engine by ensuring complete vaporization of the fuel entering the intake manifold. As such, the power developed by the engine is increased, and the level of pollutants is reduced.